The present invention relates generally to fluid pumps, and in particular, a fluid pump with a closed loop pressure regulation system for maintaining a constant pressure.
Pumps are often integral parts of tools utilized by both professionals and laymen alike to accomplish a given task more efficiently and professionally. One such example is the pump used in a paint sprayer. However, while easing the burden of the task, these tools also suffer at times from a number of distinct disadvantages. Among them is the fact that a motor directly drives the pump responsible for the application of a fluidized material under pressure.
Typically, actuating the motor between the xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d positions alternately engages and disengages a pump. When the motor is turned on, it may require some time before it can realize its full power. Unfortunately, the time it takes the motor to come to full power also affects the pressure level of the pump. That is, the pump may not reach its desired pressure level until after the motor reaches full power. Further, once the desired pressure level is reached, the pressure continues to build, thereby causing the fluidized material to drip. Not only does this result in the uneven application of the fluidized material, it generally creates a mess that needs to be cleaned. Thus, there remains a need for a pump that can maintain a substantially constant pressure.
One embodiment of the present invention comprises a multi-stage fluid pump having a closed-loop pressure regulation system interconnecting a motor and a material pump. The closed loop pressure regulation system comprises a pressure regulator, a hydraulic pump connected to and driven by the motor, and an impeller connected between the hydraulic pump and the material pump. The motor drives the hydraulic pump to circulate a fluid through the closed loop pressure regulation system at a substantially constant first pressure level. The closed loop system, in turn, drives the material pump to deliver a fluidized material at a substantially constant second pressure level from a material reservoir to a material dispenser. The first pressure level and the second pressure level are substantially equal.
The multi-stage fluid pump may be used to drive a paint sprayer, for example. The paint sprayer includes a pump that interconnects a paint reservoir and an outlet valve, a motor, a trigger mechanism operatively connected to the outlet valve, and a closed loop pressure regulation system interconnecting the motor and the pump. The motor drives the closed loop pressure regulation system to circulate a fluid through the closed loop system at a first pressure, which then drives the pump to deliver paint from the reservoir to the outlet valve at a second pressure level. As above, both the first and second pressures are generally constant and substantially equal.